1. Technical Field
The present disclosure relates to a printing device that delivers recording paper from a paper roll held in a roll paper holder and prints with a printhead.
2. Related Art
Roll paper printers (printing devices) that hold a roll of continuous recording paper wound into a roll, and deliver the paper from the paper roll for printing, are common. In the roll paper printer described in JP-A-H4-308776, for example, the recording paper delivered from a paper roll inside a roll paper holder passes between a platen roller and printhead, and is conveyed by rotation of the platen roller (conveyance roller). The roll paper printer disclosed in JP-A-H4-308776 can be used in two positions, with the back side down, or with the bottom down. The printer in JP-A-H4-308776 has a shape that can hold the paper roll stable when the roll diameter becomes small at the position that is the bottom of the roll paper holder when the bottom of the printer is down, and at the position that is the bottom of the roll paper holder when the back of the printer is down.
When slack develops in the recording paper on the path in the roll paper printer from inside the roll paper holder to the platen roller, the recording paper cannot be conveyed stably and conveyance precision may drop. The path of the recording paper may also change when the diameter of the paper roll changes or the position in which the roll paper printer is used changes, and this may cause the angle at which the recording paper contacts the platen roller to change. When this happens, the paper feed force is not stable and conveyance precision may drop.
JP-A-H9-295436 discloses a printer having a pair of top and bottom guide panels disposed in the paper path toward the printing position (image transfer position). The recording paper is supplied between these guide panels to the printing position. By using such guide panels in the roll paper printer disclosed in JP-A-H9-295436, a change in the path through which the recording paper passes can be prevented due to a change in the diameter of the paper roll or a change in the position in which the printer is used. As a result, slack can be prevented from developing in the recording paper, and recording paper conveyance precision can be maintained.
A paper detection unit may also be disposed between the roll paper holder and the printhead in a roll paper printer to detect the recording paper on the upstream side of the printhead. For example, a paper detection unit that detects the paper by means of a paper detection lever contacting the recording paper may be used. However, the recording paper may be deformed by contact with the paper detection lever in this type of paper detection unit, potentially leaving detection marks on the paper or causing wrinkles. Such deformation of the recording paper can be prevented by defining the paper path with guide panels, for example, but disposing the guide panels so they do not interfere with the paper detection lever is difficult and incompatible with reducing printer size. If the paper path from the roll paper holder to the platen roller changes according to the diameter of the paper roll or the position in which the printer is installed for use, simply detecting the paper with a paper detection lever becomes difficult.